Dr. Li Li Profile

Dr. Li Li

at Tipd LLC

SPIE Involvement:

Author

Publications (4)

Proceedings Article | 21 August 2009 Paper

Dielectric and electrical properties of sol-gel/DNA blends

R. Norwood, C. DeRose, R. Himmelhuber, N. Peyghambarian, J. Wang, L. Li, F. Ouchen, J. Grote

Proceedings Volume 7403, 74030A (2009) https://doi.org/10.1117/12.830978

KEYWORDS: Dielectrics, Sol-gels, Capacitors, Thin films, Polymers, Dielectric breakdown, Temperature metrology, Polymer thin films, Capacitance, Glasses

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Proceedings Article | 21 February 2007 Paper

An all-fiber approach for in-phase supermode phase-locked operation of multicore fiber lasers

L. Li, A. Schülzgen, V. Temyanko, H. Li, J. Moloney, N. Peyghambarian

Proceedings Volume 6453, 64531K (2007) https://doi.org/10.1117/12.701173

KEYWORDS: Fiber lasers, Optical fibers, Dielectric mirrors, Free space optics, Mirrors, Reflectivity, Fusion splicing, Cladding, Free space, Waveguides

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Proceedings Article | 20 February 2007 Paper

A hybrid sol-gel reverse-mesa waveguide using lanthanide phosphate nanoparticles for optical amplification

Haiyong Gan, Li Li, Christopher DeRose, Robert Norwood, Channa De Silva, Zhiping Zheng, Nasser Peyghambarian

Proceedings Volume 6469, 64690B (2007) https://doi.org/10.1117/12.700876

KEYWORDS: Nanoparticles, Erbium, Waveguides, Sol-gels, Ytterbium, Lanthanum, Ions, Refractive index, Nanocomposites, Optical amplifiers

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Organic-inorganic hybrid sol-gel materials have been widely used for the fabrication of optoelectronic devices due to advantages such as low cost, low loss, low temperature fabrication, ease of processing, good thermal and mechanical stability, and large refractive index tunability. However, the residual OH-like groups remaining after low temperature treatment have hindered the development of the erbium doped waveguide amplifiers working at ~1550 nm. A variety of means have been adopted to overcome this problem: (1) low vibration energy deuterated or fluorinated polymers have been applied as matrix materials; (2) erbium ions have been incorporated into organic or inorganic complexes for protection and the ligands of the complexes have been further modified to reduce the vibrational energy or increase the pump energy transfer efficiency; and (3) the erbium ions have been shielded in inorganic nanoparticles or other micro-structures. Doping erbium ions along with ytterbium ions to increase the pumping efficiency in lanthanum phosphate nanoparticles appears to be a very promising approach since (i) the emission lifetime is fairly long; (ii) at ~1550 nm the nanoparticles are transparent and have a refractive index very close to that of standard optical fiber; and (iii) the nanoparticles are highly dispersible in most organic media. Here we demonstrate how Er³⁺/Yb³⁺ containing lanthanum phosphate nanoparticles dispersed in an organically modified sol-gel can be used in a reverse mesa waveguide to achieve optical signal enhancement. Er³⁺/Yb³⁺ containing lanthanum phosphate nanoparticles have been synthesized with a molar ratio of La:Yb:Er = 76:21:3 and dispersed in cyclopentanone with 30wt% hydrolyzed MAPTMS. The composite has been incorporated into a 4mm reverse mesa waveguide prepared using an organic-inorganic hybrid sol-gel material based on MAPTMS and zirconium n-propoxide. An optical signal enhancement of ~2 dB/cm at 1527 nm has been obtained using a 200 mW 980 nm pump laser. Modeling analyses have shown that the overall performance can be further improved. The results indicate that such hybrid sol-gel reverse mesa waveguides using Er³⁺/Yb³⁺ containing lanthanum phosphate nanoparticles are very promising for optical amplifiers in integrated optical systems.

Proceedings Article | 30 August 2005 Paper

Lanthanide nanoparticle doped low-loss sol-gel amplifier materials

Haiyong Gan, Robert Norwood, Li Li, Christopher DeRose, Jianfeng Wu, Jayan Thomas, M. Amir Fardad, Axel Schuelzgen, Nasser Peyghambarian, Channa De Silva, Zhiping Zheng

Proceedings Volume 5935, 59350D (2005) https://doi.org/10.1117/12.619565

KEYWORDS: Erbium, Nanoparticles, Sol-gels, Ions, Lanthanum, Refractive index, Waveguides, Polymers, Absorption, Optical amplifiers

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Organic-inorganic hybrid sol-gel materials have attracted increasing attention in recent years as low-cost, rugged materials for integrated optical devices such as optical couplers, splitters, and electro-optic modulators. These materials can be easily processed by spin-coating, wet-etching photolithography, and low-temperature baking. Precise control of waveguide core-cladding refractive indices produces well-confined low-loss propagation and good matching of the absolute refractive index to that of fused silica results in low optical coupling loss to optical fiber. The increased thermal and mechanical stability of these materials, relative to optical polymers, results in numerous packaging options and improved reliability. However organic-inorganic hybrid sol-gel materials have not yet been often used as host of active dopants such as erbium (III) ions for 1550nm optical amplification. This limitation owes primarily to matrix and chelate dominated nonradiative relaxation processes, as high phonon energy OH and OH-like oscillators can bridge off the energy from the excited erbium (III) ions at very high rates. Different strategies have been proposed to protect erbium (III) ions from matrix and chelate quenching, including host and ligand fluorination, and inorganic microstructure shielding. Here we report on our work of encapsulating erbium (III) ions in transparent, refractive index matched, and highly re-dispersible lanthanum phosphate nanoparticles and the work of examining the optical properties of these nanoparticles as active dopants in organic-inorganic hybrid sol-gels adopting 2-methacryloxypropyl trimethoxysilane (MAPTMS) as a precursor. 980nm laser pumped photoluminescence at 1535nm was obtained from solid bulk samples of 300mg La.₉₉Er.₀₁PO₄ nanoparticles doped in 1mL hybrid sol-gel. Thick bulk samples of this composition exhibited exceptional clarity and little trace of nanoparticle scattering effects. The lifetime of the nanoparticle doped hybrid sol-gel composite was measured to be 220μs, indicating an intermediate relaxation rate between that of an erbium organic complex and annealed erbium doped glass. La.₉₉Er.₀₁PO₄ nanoparticle doped hybrid sol-gel films were also prepared and the refractive index was measured to be 1.4966 at 1550nm, which is very close to that of optical fiber and provides a suitable index difference from an undoped and metal oxide tuned sol-gel at 1.4870 to comprise an efficient single-mode waveguide system.

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